Attack and defense in conspecific fighting in tree shrews (Tupaia belangeri)

Principles of conspecific defense have been analyzed for rodents, in which specific target sites for biting by attackers on defenders serve as an important determinant of the actions involved in both attacker and defender behavior. In an effort to determine the generality of these principles, attack and defensive behaviors and target sites for biting attack were evaluated in a nonrodent species, the tree shrew (Tupaia belangeri). Brief daily and repeated conspecific dyadic encounters between adult, socially experienced males (dominants, attackers), and adult, socially naive males (subordinates, defenders) that had been transferred into the territory of the dominants, produced a polarization of attack and defense. The dominant males showed chase, chase attack, jump attack, and biting behaviors, while the subordinates displayed flight and freezing. The vast majority of bites, as well as wounds and bruises, were on the subordinates’ backs. These patterns are very similar to those previously found in rats and mice and suggest that the organization of fighting, with targets of biting (or other painful) attack serving as an important determinant of both attacker (dominant) and defender (subordinate) behavior, may show considerable generality across nonrodent as well as rodent species. Although relatively few wounds were found after 28 days of repeated and daily encounters, the subordinate tree shrews show a variety of behavioral, neuroendocrine, and central nervous changes, indicating that they are stressed by these encounters per se. Aggr. Behav. 27:139–148, 2001. © 2001 Wiley‐Liss, Inc.     

Effects of verb complexity on speech errors

Two experiments examined whether semantically related verbs that contrast with respect to the absence versus the presence of an additional semantic feature differentially compete for selection during the encoding of a sentence for production. In both experiments, a speech error induction task was used to elicit contextual (misordering) errors involving semantically related verbs that contrasted only in their semantic complexity or in both their semantic and morphophonological complexity. The prediction was that an asymmetry in contextual errors would be observed in which the more complex verbs would replace the simpler verbs more often than the reverse. This prediction was confirmed in both experiments, with more perseverations and anticipations involving the semantically more complex verb of antonym pairs in Experiment 1, and more perseverations and anticipations involving the semantically more-specified verb of a heavy-light pair in Experiment 2. The implications of the results for spreading-activation theories of language production are discussed.     

Language comprehension vs. language production: age effects on fMRI activation

Normal language acquisition is a process that unfolds with amazing speed primarily in the first years of life. However, the refinement of linguistic proficiency is an ongoing process, extending well into childhood and adolescence. An increase in lateralization and a more focussed productive language network have been suggested to be the neural correlates of this process. However, the processes underlying the refinement of language comprehension are less clear. Using a language comprehension (Beep Stories) and a language production (Vowel Identification) task in fMRI, we studied language representation and lateralization in 36 children, adolescents, and young adults (age 6-24 years). For the language comprehension network, we found a more focal activation with age in the bilateral superior temporal gyri. No significant increase of lateralization with age could be observed, so the neural basis of language comprehension as assessed with the Beep Stories task seems to be established in a bilateral network by late childhood. For the productive network, however, we could confirm an increase with age both in focus and lateralization. Only in the language comprehension task did verbal IQ correlate with lateralization, with higher verbal IQ being associated with more right-hemispheric involvement. In some subjects (24%), language comprehension and language production were lateralized to opposite hemispheres.     

Examination of the influence of contingency on changes in reinforcer value

This study examined how the amount of effort required to produce a reinforcer influenced subsequent preference for, and strength of, that reinforcer in 7 individuals with intellectual disabilities. Preference assessments identified four moderately preferred stimuli for each participant, and progressive-ratio (PR) analyses indexed reinforcer strength. Stimuli were then assigned to one of four conditions for 4 weeks: fixed-ratio (FR) 1 schedule, escalating FR schedule, yoked noncontingent (NCR) delivery, and restricted access. Preference assessments and PR schedules were then repeated to examine changes in selection percentages and PR break points. Selection percentages decreased for all NCR stimuli but increased for most of the restricted stimuli. There were no systematic changes in selection percentages for either of the contingent stimuli. Break points increased, on average, for all conditions, but the increase was highest for the restricted stimuli and lowest for the NCR stimuli. These results are discussed in relation to recent basic research addressing the influence of effort on stimulus value.     

How do people react to negative procedures? On the moderating role of authority’s biased attitudes

The authors focus on the effects an authority’s apparent inconsistency between persons on judgments of relational treatment and procedural justice following negative procedures (i.e., procedures that people commonly regard as unfair). In Experiment 1, participants responded most negatively following a procedure that denied them, but granted another participant, an opportunity to voice an opinion when the intergroup context raised suspicions of bias (i.e., when both the experimenter and another participant were outgroup members). In Experiment 2, participants responded most negatively when the experimenter had expressed biased attitudes in favor of another participant, but this effect occurred only following procedures that denied participants a voice opportunity. We conclude that authority’s biased attitudes help people to make sense of negative procedure information.     

Use of a multicomponent treatment for food refusal

We examined the use of a multicomponent treatment for food refusal exhibited by a 5-year-old boy who had been diagnosed with mild to moderate mental retardation. Treatment consisted of access to highly preferred tangible items, which were removed contingent on problem behavior or not accepting a bite, and differential reinforcement of alternative behavior. Treatment resulted in an increase in food acceptance to 100% of bite offers and near-zero rates of problem behavior. In addition, the participant's caregivers were successfully trained to implement the treatment.     

Procedural justice and status: status salience as antecedent of procedural fairness effects

The current article explores status as an antecedent of procedural fairness effects (the findings that perceived procedural fairness affects people's reactions, e.g., their relational judgments). On the basis of the literature, the authors proposed that salience of the general concept of status leads people to be more attentive to procedural fairness information and that, as a consequence, stronger procedural fairness effects should be found. In correspondence with this hypothesis, Experiment 1 showed stronger procedural fairness effects on people's relational treatment evaluations in a status salient condition compared with a control condition. Experiment 2 replicated this effect and, in further correspondence with the hypothesis, showed that status salience led to increased cognitive accessibility of fairness concerns. Implications for the psychology of procedural justice are discussed.     

Social identification and permeability of group boundaries

Two experiments were conducted to investigate some of the factors affecting social identification. In Experiment 1 ingroup identification was measured for subjects who were members of high or low status groups with either permeable or impermeable boundaries, and who received high, average or low ability feedback. The main results are that (1) members of high status groups show more ingroup identification than members of low status groups (2) members of low status groups with permeable boundaries identify less with their group than members of low status groups with impermeable boundaries and (3) in low status groups ingroup identification decreases as group members have higher individual ability. In Experiment 2, in addition to manipulating group status and individual ability, permeability was further differentiated into separate possibilities for upward and downward mobility. The most important results of Experiment 2 are that (1) members of high status groups show more ingroup identification than members of low status groups and (2) group members with high individual ability identify less with their group when upward mobility is possible than when upward mobility is not possible. These results are discussed in relation to social identity theory.     

Social comparison on two dimensions

In this experiment social comparison on two task dimensions has been studied. The subjects received bogus feedback on their performance on two tests, one allegedly measuring creativity, the other alertness. By means of this feedback four relative position conditions were induced: scoring high on both tests, scoring low on both tests, scoring high on creativity and low on alertness, and vice versa. Anticipating either a co-operative or a competitive game, the subjects indicated their preference for one or the other task dimension and also expressed their preference for a comparison person. It was found that, as predicted, the subjects preferred and valued comparison dimensions on which they occupied a favourable position. With respect to preference for a comparison person, compensatory choices were obtained: on the dimension on which the subject performed well, they preferred an inferior other. On the dimension on which they performed poorly, they preferred a superior other. This pattern of choices was found in co-operation as well as in competition. Finally, upward preference was stronger in co-operative than in competitive conditions, particularly on the dimension on which the subject's own score was low. These and other results were discussed in relation to theoretical social comparison notions.